Even if the call wasn’t picked up, the surveillance software could still be installed because of that “vulnerable VOIP” not being secure enough.

The call then may have disappeared from the device’s call log because hackers had control of the app.

Image copyrightGetty ImagesImage caption Updates on most social media apps include security improvements

And no, the fix isn’t just a case of turning your phone off and on again.

On Monday, WhatsApp suggested its 1.5 billion users update the app after rolling out a fix to help protect devices from cyber attacks.

You’ll have to do this one manually so that little red dot hovering above App Store (or whatever your phone does to give you a passive-aggressive nudge) isn’t going to take care of itself this time.

Even though messages in WhatsApp are end-to-end encrypted, which means they should only appear on the sender or recipient’s device, the surveillance software used in the latest hack would have let an attacker read the target’s messages.

It’s probably best to keep on top of all your app updates as they often include tweaks to security.

Get off the cloud

You probably know about end-to-end encryption – one of the biggest appeals of WhatsApp.

But if you – or your friends – back up your WhatsApp chats to a service like Google Drive or iCloud, there is a flaw.

That back-up is not protected by end-to-end encryption, so anyone with access to your cloud could get hold of your chat history.

So if you really care about privacy, then that’s something you might want to disable.

You might get the odd prompt asking how often you want backups – but if you want to change it now then head to the Chat Backup area of your settings.

Sweet 2FA

Image copyrightGetty ImagesImage caption You’re not fooling anyone with that sinister hoodie and no face, pal

If your app supports it (which WhatsApp does), two-factor authentication (2FA) is a good way to help keep data safe.

This is an extra layer of security to make sure people trying to gain access to an online account are who they say they are.

First, a user will enter their username and a password. Then, instead of immediately gaining access, they’ll be required to provide a finger print, a voice command, or a code texted to your mobile device for example. Sometimes it’s some extra information. You know the drill: first pet, mother’s maiden name – those guys.

Again you can change two-step verification in your settings in WhatsApp.